A small domestic waste catalytic pyrolysis treatment system

Abstract

The present invention discloses a small domestic waste catalytic pyrolysis treatment system, which includes a pyrolysis furnace, a secondary combustion chamber, a flue gas quenching and acid removal device, a lime powder adding device, a closed domestic waste screening and flue gas tar interception device, a high-voltage electrostatic deacidification, dust removal and dehumidification device, and a chimney that are connected in sequence. According to the characteristics of large porosity of domestic waste and the carbonation reaction of CaO catalyzing the pyrolysis gasification of domestic waste, the present invention uses a closed domestic waste screening and flue gas tar interception device to achieve an effective combination of domestic waste screening, drying and flue gas tar interception, effectively solve the problem of blockage of the subsequent treatment system by tar in the flue gas, improve the operation stability of the system, and at the same time increase the calorific value of domestic waste, the subsequent domestic waste pyrolysis reaction temperature and the hydrogen production efficiency, effectively reduce the content of pollutants such as tar and dioxins in the flue gas, and have significant environmental benefits.

Description

Technical Field

[0001] The present invention relates to a small domestic waste catalytic pyrolysis treatment system. Background Art

[0002] In recent years, with the increasing demand for on-site treatment of domestic waste in remote small and medium-sized towns, nature reserves and other areas with long transportation distances and high transportation risks, the domestic waste pyrolysis gasification technology in China has achieved certain development and is gradually replacing the original technologies such as sanitary landfill, composting, and waste incineration power generation. However, from the actual operation of domestic waste pyrolysis gasification treatment projects in China, there are still various problems as follows: The treatment scale of a single device for domestic waste pyrolysis gasification is small, the yield of combustible gas is relatively low, and the subsequent pyrolysis gasification reaction temperature of some domestic waste pyrolysis gasification facilities is low (lower than 850 °C) due to the failure to screen the inorganic components in the waste, which further increases the tar content and treatment difficulty in the domestic waste pyrolysis gasification flue gas; In some projects that use dry methods to treat domestic waste pyrolysis gasification flue gas, the tar is not effectively treated, seriously blocking the flue gas pipelines and facilities, affecting the normal operation of the flue gas treatment facilities, and greatly increasing the environmental risk of flue gas emissions.

[0003] With the in-depth implementation of the domestic waste classification system, organic components such as waste paper and waste plastics in domestic waste will be recycled, and the organic components in the classified domestic waste will be greatly reduced. It is expected that by the end of 2020, the resource recovery utilization rate of domestic waste will reach more than 35%. As a result, the calorific value of the domestic waste used for pyrolysis gasification treatment after sorting becomes lower, the temperature of the domestic waste pyrolysis furnace decreases, resulting in a decrease in the production volume and quality of combustible gas during the domestic waste pyrolysis process, thus causing the domestic waste pyrolysis gasification reaction system to enter a vicious cycle, and ultimately the pyrolysis gasification facility may not operate properly or even stop operating due to the low calorific value of domestic waste. Summary of the Invention

[0004] The present invention aims to provide a small domestic waste catalytic pyrolysis treatment system for the problems of reduced calorific value of domestic waste caused by the in-depth implementation of the domestic waste classification scheme and the phenomenon that most domestic waste pyrolysis gasification treatment facilities cannot operate stably due to problems such as low yield of combustible gas in existing domestic waste pyrolysis gasification, low pyrolysis gasification reaction temperature, large output of tar in flue gas and difficult treatment.

[0005] In order to achieve the above object, the technical solution provided by the present invention is as follows:

[0006] The small domestic waste catalytic pyrolysis treatment system includes a pyrolysis furnace (1), a secondary combustion chamber (3), a flue gas quenching and acid removal device (4), a lime powder adding device (5), a closed domestic waste screening and flue gas tar interception device (6), a high-voltage electrostatic acid removal, dust removal and dehumidification device (9) and a chimney (10); the flue gas pipeline (2) of the pyrolysis furnace (1) is communicated with the flue gas inlet of the secondary combustion chamber (3), the flue gas outlet of the secondary combustion chamber (3) is communicated with the flue gas inlet of the flue gas quenching and acid removal device (4), the flue gas outlet of the flue gas quenching and acid removal device (4) is communicated with the flue gas inlet of the Venturi type activated carbon and lime powder adding device (5), the flue gas outlet of the Venturi type activated carbon and lime powder adding device (5) is communicated with the flue gas inlet of the closed domestic waste screening and flue gas tar interception device (6), the flue gas outlet of the closed domestic waste screening and flue gas tar interception device (6) is communicated with the flue gas inlet of the high-voltage electrostatic acid removal, dust removal and dehumidification device (9), and the flue gas outlet of the high-voltage electrostatic acid removal, dust removal and dehumidification device (9) is communicated with the chimney (10); one end of the closed domestic waste screening and flue gas tar interception device (6) far from the flue gas inlet is provided with a domestic waste feed port (15), and one end close to the flue gas inlet is provided with a domestic waste discharge port (13), and the domestic waste discharge port (13) is communicated with the feed port (14) of the pyrolysis furnace (1).

[0007] Preferably, a pipeline type segmented shaftless spiral domestic waste screening and conveying device (7) is arranged in the inner cavity of the closed domestic waste screening and flue gas tar interception device (6); the pipeline of the pipeline type segmented shaftless spiral domestic waste screening and conveying device (7) close to the domestic waste feed port (15) is provided with sieve holes, and a sterilized closed sleeve for undersize (8) is sleeved outside the pipeline provided with the sieve holes, and a sterilized closed sleeve outlet (16) for undersize is arranged at the bottom of the sterilized closed sleeve for undersize (8).

[0008] Preferably, the cross section of the pipeline type segmented shaftless spiral domestic waste screening and conveying device (7) is circular; the cross section of the sterilized closed sleeve for undersize (8) is U-shaped.

[0009] Preferably, the small domestic waste catalytic pyrolysis treatment system further includes an alkali liquor tank (11), a spray port (12) is arranged on the upper part of the flue gas quenching and acid removal device (4), and the alkali liquor tank (11) is communicated with the spray port (12).

[0010] Preferably, the Venturi type activated carbon and lime powder adding device (5) is provided with a feed port at the neck pipe of the Venturi and annular alkali liquor spray holes at the diffuser pipe.

[0011] Preferably, the flue gas pipeline (2) of the pyrolysis furnace (1) is arranged in the middle and lower part of the pyrolysis furnace (1).

[0012] The present invention will be further described below in combination with the design and working principle:

[0013] In the small domestic waste catalytic pyrolysis treatment system of the present invention, a closed domestic waste screening and flue gas tar interception device is provided. A pipeline-type segmented shaftless screw domestic waste screening and conveying device is arranged inside the closed domestic waste screening and flue gas tar interception device. Screen holes are provided in the waste feeding section, and no screen holes are provided in the discharging section, so as to effectively intercept tar, activated carbon and lime powder in the flue gas, improve the calorific value of domestic waste and the generation rate of combustible gas in subsequent pyrolysis gasification; A closed sleeve is sleeved outside the screen hole section of the shaftless screw, and a disinfected collection hopper for undersize materials is arranged on the inner wall of the waste feeding end, so as to perform high-temperature sterilization treatment on the domestic waste undersize materials and discharge them regularly; That is to say, domestic waste enters the front section of the shaftless screw conveyor with screen holes arranged on the pipe wall from the outlet of the feeding hopper. The inorganic particles in the domestic waste fall into the undersize material sterilization closed sleeve through the screen holes, and the remaining domestic waste enters the pyrolysis furnace through the rear section of the screw conveyor without screen holes on the pipe wall; After the function of high-temperature disinfection of the undersize materials is completed in the undersize material sterilization closed sleeve, the undersize materials are scraped out from the outlet of the undersize material sterilization closed sleeve; The flue gas enters the pipeline-type segmented shaftless screw domestic waste screening and conveying device from the flue gas inlet. The high-temperature flue gas and domestic waste move in opposite directions in the pipeline-type segmented shaftless screw domestic waste screening and conveying device. After the flue gas and domestic waste are in reverse contact, they enter the high-voltage electrostatic deacidification, dust removal and dehumidification device from the flue gas outlet.

[0014] During the conveying process of domestic waste in the closed domestic waste screening and flue gas tar interception device, the components with small particle size in the waste (mainly inorganic substances) are transferred into the closed sleeve through the perforated section of the shaftless rolling screen. The high-temperature tail gas (temperature about 300°C) is in direct contact with the undersize materials, and the undersize materials can be heated to about 200°C, which can effectively complete the high-temperature sterilization and disinfection of the domestic waste undersize materials, and the sterilized undersize materials are discharged through the undersize material collection hopper at the feeding end. The components that cannot pass through the screen holes of the shaftless rolling screen (mainly organic substances) are pushed forward with the spiral of the rolling screen. After being in direct reverse contact with the hot flue gas (the residence time of domestic waste is kept at 20 minutes), the domestic waste can be heated to about 250°C, and the drying of domestic waste in this device is basically completed. Tar, activated carbon, lime powder, etc. in the hot flue gas are effectively intercepted by the domestic waste. Among them, tar and activated carbon increase the calorific value of domestic waste, and at the same time greatly reduce the content of tar and dioxin in the subsequent flue gas, effectively solving the problem of blockage of pipelines and flue gas treatment facilities by tar, and improving the stability of system operation; In addition, the intercepted lime powder enters the subsequent pyrolysis gasification process together with the domestic waste, and through the carbonation reaction of CaO (absorbing CO 2 ), catalyze the generation of combustible gases such as H 2 etc., increasing the calorific value of the combustible gas and the temperature of the pyrolysis gasification reaction.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] (1) Effectively intercepts tar and improves the stability of system operation. By taking advantage of the large porosity of domestic waste, a flue gas interception and purification system with domestic waste as the medium is constructed to efficiently intercept tar in a closed device, reduce the tar entering the subsequent flue gas system, lower the failure rate caused by blockage of pipelines and flue gas treatment facilities, and ensure the stable operation of the domestic waste pyrolysis system.

[0017] (2) Highly efficient catalysis to increase the pyrolysis gasification reaction temperature. By utilizing the carbonation reaction of CaO, the CO generated during the pyrolysis gasification reaction 2 is effectively absorbed, which to a certain extent improves the yield and quality of H in the pyrolysis gasification of domestic waste, increases the heat generated by the combustion of combustible gas, and further raises the pyrolysis gasification reaction temperature (>850 °C), promoting the effective decomposition of pollutants such as dioxins and tar. 2

[0018] (3) Integrated closed screening and disinfection, with remarkable garbage treatment efficiency and environmental benefits. A closed combined device is used to effectively separate the small particle size components in the garbage, reducing the amount of domestic waste, enhancing the relative calorific value of the domestic waste participating in the pyrolysis gasification reaction, and improving the domestic waste treatment efficiency; in addition, the undersize is directly disinfected in a closed environment by high-temperature flue gas, avoiding the impact of malodorous gases on the environment and showing remarkable environmental benefits.

[0019] In summary, the small domestic waste catalytic pyrolysis treatment system described in the present invention utilizes the characteristics of large porosity of domestic waste and the carbonation reaction of CaO to catalyze the pyrolysis gasification of domestic waste. Through a closed domestic waste screening and flue gas tar interception device, an effective combination of domestic waste screening, drying and flue gas tar interception is achieved, effectively solving the problem of blockage of the subsequent treatment system by tar in the flue gas, improving the system operation stability, while increasing the calorific value of domestic waste, the subsequent pyrolysis reaction temperature of domestic waste and the hydrogen production efficiency, and effectively reducing the content of pollutants such as tar and dioxins in the flue gas, with remarkable environmental benefits. Description of the Drawings

[0020] Figure 1 is a schematic structural diagram of the small domestic waste catalytic pyrolysis treatment system of the present invention;

[0021] Figure 2 is a cross-sectional view of the closed domestic waste screening and flue gas tar interception device of the present invention.

[0022] In the figure: 1. Pyrolysis furnace, 2. Flue gas pipeline of pyrolysis furnace, 3. Secondary combustion chamber, 4. Flue gas rapid cooling and acid removal device, 5. Venturi type activated carbon and lime powder adding device, 6. Enclosed domestic waste screening and flue gas tar interception device, 7. Pipeline type segmented shaftless spiral domestic waste screening and conveying device, 8. Sterilization closed casing for undersize, 9. High-voltage electrostatic acid removal, dust removal and dehumidification device, 10. Chimney, 11. Alkali liquid pool, 12. Spray port, 13. Domestic waste discharge port, 14. Feed port, 15. Domestic waste feed port, 16. Outlet of sterilization closed casing for undersize. Detailed implementation mode

[0023] See Figure 1 and Figure 2 , the small domestic waste catalytic pyrolysis treatment system includes a pyrolysis furnace 1, a secondary combustion chamber 3, a flue gas rapid cooling and acid removal device 4, a lime powder adding device 5, an enclosed domestic waste screening and flue gas tar interception device 6, a high-voltage electrostatic acid removal, dust removal and dehumidification device 9 and a chimney 10; the flue gas pipeline 2 of the pyrolysis furnace 1 is communicated with the flue gas inlet of the secondary combustion chamber 3, the flue gas outlet of the secondary combustion chamber 3 is communicated with the flue gas inlet of the flue gas rapid cooling and acid removal device 4, the flue gas outlet of the flue gas rapid cooling and acid removal device 4 is communicated with the flue gas inlet of the Venturi type activated carbon and lime powder adding device 5, the flue gas outlet of the Venturi type activated carbon and lime powder adding device 5 is communicated with the flue gas inlet of the enclosed domestic waste screening and flue gas tar interception device 6, the flue gas outlet of the enclosed domestic waste screening and flue gas tar interception device 6 is communicated with the flue gas inlet of the high-voltage electrostatic acid removal, dust removal and dehumidification device 9, and the flue gas outlet of the high-voltage electrostatic acid removal, dust removal and dehumidification device 9 is communicated with the chimney 10; a domestic waste feed port 15 is arranged at one end of the enclosed domestic waste screening and flue gas tar interception device 6 far away from the flue gas inlet, a domestic waste discharge port 13 is arranged at one end close to the flue gas inlet, and the domestic waste discharge port 13 is communicated with the feed port 14 of the pyrolysis furnace 1.

[0024] Wherein, a pipeline type segmented shaftless spiral domestic waste screening and conveying device 7 is arranged in the inner cavity of the enclosed domestic waste screening and flue gas tar interception device 6; a screen hole is arranged on the pipeline of the pipeline type segmented shaftless spiral domestic waste screening and conveying device 7 close to the domestic waste feed port 15, a sterilization closed casing 8 for undersize is sleeved outside the pipeline provided with the screen hole, and a sterilization closed casing outlet 16 for undersize is arranged at the bottom of the sterilization closed casing 8 for undersize. The cross section of the pipeline type segmented shaftless spiral domestic waste screening and conveying device 7 is circular; the cross section of the sterilization closed casing 8 for undersize is U-shaped. The small domestic waste catalytic pyrolysis treatment system further includes an alkali liquid pool 11, a spray port 12 is arranged on the upper part of the flue gas rapid cooling and acid removal device 4, and the alkali liquid pool 11 is communicated with the spray port 12. The Venturi type activated carbon and lime powder adding device 5 is provided with a feed port at the neck pipe of the Venturi and annular alkali liquid spray holes at the diffuser pipe. The flue gas pipeline 2 of the pyrolysis furnace 1 is arranged at the middle and lower part of the pyrolysis furnace 1.

[0025] The small domestic waste catalytic pyrolysis treatment system makes full use of the characteristics of large porosity of domestic waste and the carbonation reaction of CaO to catalyze the pyrolysis gasification of domestic waste, so that the treatment efficiency of the system is increased by about 25%, and the problems of tar clogging the flue gas pipeline and treatment facilities are solved.

Claims

1. A small domestic waste catalytic pyrolysis treatment system, characterized in that, the small domestic waste catalytic pyrolysis treatment system includes a pyrolysis furnace (1), a secondary combustion chamber (3), a flue gas quenching and acid removal device (4), a lime powder adding device (5), a closed domestic waste screening and flue gas tar interception device (6), a high-voltage electrostatic deacidification, dust removal and dehumidification device (9) and a chimney (10); the flue gas pipeline (2) of the pyrolysis furnace (1) is communicated with the flue gas inlet of the secondary combustion chamber (3), the flue gas outlet of the secondary combustion chamber (3) is communicated with the flue gas inlet of the flue gas quenching and acid removal device (4), the flue gas outlet of the flue gas quenching and acid removal device (4) is communicated with the flue gas inlet of the Venturi-type activated carbon and lime powder adding device (5), the flue gas outlet of the Venturi-type activated carbon and lime powder adding device (5) is communicated with the flue gas inlet of the closed domestic waste screening and flue gas tar interception device (6), the flue gas outlet of the closed domestic waste screening and flue gas tar interception device (6) is communicated with the flue gas inlet of the high-voltage electrostatic deacidification, dust removal and dehumidification device (9), and the flue gas outlet of the high-voltage electrostatic deacidification, dust removal and dehumidification device (9) is communicated with the chimney (10); one end of the closed domestic waste screening and flue gas tar interception device (6) far from the flue gas inlet is provided with a domestic waste feed port (15), and one end close to the flue gas inlet is provided with a domestic waste discharge port (13), and the domestic waste discharge port (13) is communicated with the feed port (14) of the pyrolysis furnace (1); a pipeline-type segmented shaftless spiral domestic waste screening and conveying device (7) is arranged in the inner cavity of the closed domestic waste screening and flue gas tar interception device (6); the pipeline of the pipeline-type segmented shaftless spiral domestic waste screening and conveying device (7) close to the domestic waste feed port (15) is provided with sieve holes, and a sieve-bottom material sterilization closed sleeve (8) is sleeved outside the pipeline provided with the sieve holes, and the bottom of the sieve-bottom material sterilization closed sleeve (8) is provided with a sieve-bottom material sterilization closed sleeve outlet (16); the small domestic waste catalytic pyrolysis treatment system further includes an alkali liquor tank (11), a spray port (12) is arranged on the upper part of the flue gas quenching and acid removal device (4), and the alkali liquor tank (11) is communicated with the spray port (12).

2. The small domestic waste catalytic pyrolysis treatment system according to claim 1, characterized in that, the cross sections of the pipeline-type segmented shaftless spiral domestic waste screening and conveying device (7) are all circular; the cross sections of the sieve-bottom material sterilization closed sleeve (8) are all U-shaped.

3. The small domestic waste catalytic pyrolysis treatment system according to claim 1, characterized in that, the Venturi-type activated carbon and lime powder adding device (5) is provided with a feed port at the neck pipe of the Venturi and annular alkali liquor spray holes at the diffuser pipe.

4. The small domestic waste catalytic pyrolysis treatment system according to claim 1, characterized in that, the flue gas pipeline (2) of the pyrolysis furnace (1) is arranged at the middle and lower part of the pyrolysis furnace (1).

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